Sudha Balasubramanian

Optimization and scale-up of Wharton's jelly-derived mesenchymal stem cells for clinical applications.

MSCs are promising candidates for stem cell therapy and regenerative medicine. Umbilical cord is the easiest obtainable biological source of MSCs and the Whartons jelly of the umbilical cord is a rich source of fetus-derived stem cells. However, the use of MSCs for therapeutic application is based on their subsequent large-scale in vitro expansion. A fast and efficient protocol for generation of large quantities of MSCs is required to meet the clinical demand and biomedical research needs. Here we have optimized conditions for scaling up of WJ-MSCs. Low seeding density along with basic fibroblast growth factor (bFGF) supplementation in the growth medium, which is DMEM-KO, resulted in propagation of more than 1 x 10(8) cells within a time period of 15 days from a single umbilical cord. The upscaled WJ-MSCs retained their differentiation potential and immunosuppressive capacity. They expressed the typical hMSC surface antigens and the addition of bFGF in the culture medium did not affect the expression levels of HLA-DR and CD 44. A normal karyotype was confirmed in the large-scale expanded WJ-MSCs. Hence, in this study we attempted rapid clinical-scale expansion of WJ-MSCs which would allow these fetus-derived stem cells to be used for various allogeneic cell-based transplantations and tissue engineering.

Are serum-free and xeno-free culture conditions ideal for large scale clinical grade expansion of Wharton’s jelly derived mesenchymal stem cells? A comparative study

IntroductionMesenchymal stromal/stem cells (MSCs) for clinical use have largely been isolated from the bone marrow, although isolation of these cells from many different adult and fetal tissues has been reported as well. One such source of MSCs is the Whartons Jelly (WJ) of the umbilical cord, as it provides an inexhaustible source of stem cells for potential therapeutic use. Isolation of MSCs from the umbilical cord also presents little, if any, ethical concerns, and the process of obtaining the cord tissue is relatively simple with appropriate consent from the donor. However, a great majority of studies rely on the use of bovine serum containing medium for isolation and expansion of these cells, and porcine derived trypsin for dissociating the cells during passages, which may pose potential risks for using these cells in clinical applications. It is therefore of high priority to develop a robust production process by optimizing culture variables to efficiently and consistently generate MSCs that retain desired regenerative and differentiation properties while minimizing risk of disease transmission.MethodsWe have established a complete xeno-free, serum-free culture condition for isolation, expansion and characterization of WJ-MSCs, to eliminate the use of animal components right from initiation of explant culture to clinical scale expansion and cryopreservation. Growth kinetics, in vitro differentiation capacities, immunosuppressive potential and immunophenotypic characterization of the cells expanded in serum-free media have been compared against those cultured under standard fetal bovine serum (FBS) containing medium. We have also compared the colony-forming frequency and genomic stability of the large scale expanded cells. Secretome analysis was performed to compare the angiogenic cytokines and functional angiogenic potency was proved by Matrigel assays.ResultsResults presented in this report identify one such serum-free, xeno-free medium for WJ expansion. Cells cultured in serum-free, xeno-free medium exhibit superior growth kinetics and functional angiogenesis, alongside other MSC characteristics.ConclusionsWe report here that WJ-MSCs cultured and expanded in Mesencult XF, SF Medium retain all necessary characteristics attributed to MSC for potential therapeutic use.

Comparison of chemokine and receptor gene expression between Wharton ' s jelly and bone marrow-derived mesenchymal stromal cells

BACKGROUND AIMS Because of their multilineage differentiation capacity, immunomodulatory role and homing ability, mesenchymal stromal cells (MSC) are emerging as a new therapeutic strategy for treating a variety of disorders. Although bone marrow (BM) is the best characterized source of MSC, Whartons jelly (WJ) of the umbilical cord holds great promise as an alternative. As delivery direct to the site of injury is not always feasible, efficient homing of MSC to the site of injury is critical for inducing tissue repair and regeneration. MSC express a wide variety of growth factors, chemokines and receptors that are important for cell migration, homing and re-establishment of blood supply for recovery of damaged tissues. METHODS Detailed chemokine and receptor gene expression profiles of WJ MSC were established, and subsequently compared with those of BM-derived MSC using a polymerase chain reaction (PCR) array. Secretion of growth factors was analyzed and evaluated using culture supernatant from WJ and BM MSC. RESULTS Our results revealed a differential expression pattern of the chemokines and their receptors between WJ- and BM-derived MSC. Several Glutamic acid-Leucine-Arginine; ELR-positive CXC chemokine genes and secretion of growth factors, which promote angiogenesis, were found to be up-regulated in WJ MSC. CONCLUSIONS To understand better the localization and mechanism of tissue repair by transplanted WJ MSC, we attempted chemokine and their receptor transcription profiling, followed by analysis of growth factors secreted by WJ MSC, and compared them against those of BM MSC. The data suggest that MSC from different sources can be explored for distinct therapeutic roles.

Isolation, characterization, and gene expression analysis of Wharton's jelly-derived mesenchymal stem cells under xeno-free culture conditions.

Mesenchymal stem cells (MSCs) have become an attractive tool for tissue engineering and targets in clinical transplantation due to their regeneration potential and immuno-suppressive capacity. Although MSCs derived from bone marrow are the most widely used, their harvest requires an invasive procedure. The umbilical cord, which is discarded at birth, can provide an inexhaustible source of stem cells for therapy. The Wharton’s jelly-derived MSCs (WJ-MSCs), from the umbilical cord, have been shown to have faster proliferation rates and greater expansion capability compared with adult MSCs. The standard isolation and in vitro culture protocol for WJ-MSCs utilizes fetal bovine serum (FBS) or calf serum as a nutrient supplement. However, FBS raises potential safety concerns such as transmission of viral/prion disease and may initiate xenogeneic immune reactions against bovine antigens. Therefore, for therapeutic applications, there is an urgent requirement to establish an alternative nutrient supplement which would favor cell proliferation, retain MSC characteristics, and prove safe in human subjects. In the present study, we isolated and expanded WJ-MSCs in 5% pooled, allogeneic human serum (HS) supplemented with 2 ng/mL of basic fibroblast growth factor. For cell dissociation, porcine trypsin was replaced with TrypLE, a recombinant enzyme, and a protease-free protocol was adapted for isolation of MSCs from WJ. We determined their growth kinetics, in vitro differentiation potential, surface marker expression, and colony-forming unit potential and compared them against standard WJ-MSC cultures expanded in 10% FBS. All these parameters matched quite well between the two MSC populations. To test whether there is any alteration in gene expression on switching from FBS to HS, we analyzed a panel of stem cell and early lineage markers using Taqman® low density array. No significant deviation in gene expression was observed between the two populations. Thus we established an efficient, complete xeno-free protocol for propagation of human WJ-MSCs.

Higher propensity of Wharton's jelly derived mesenchymal stromal cells towards neuronal lineage in comparison to those derived from adipose and bone marrow.

Mesenchymal stromal cells (MSCs) derived from different tissue sources are capable of differentiating into neural and glial cell types. However, the efficiency of differentiation varies between MSCs derived from different tissues. We compared the efficiency of neural progenitor population generation between adipose (AD), bone marrow (BM) and Whartons jelly (WJ) derived MSCs. MSCs isolated from the three sources were induced to form primary neurospheres using epidermal growth factor (20 ng/mL) and bFGF (20 ng/mL). The self‐renewal potential of the primary neurospheres was assessed by secondary neurosphere assay. Primary neurospheres were differentiated to neuronal lineage on fibronectin‐coated dishes. The neurospheres and the resulting differentiated cells were characterized by immunocytochemistry and the RT‐PCR analyses. We have also investigated the secretome profile of neuronal‐related growth factors using Ray biotech cytokine array. The results show that MSCs from the three sources can be induced to generate neurospheres and they expressed neural progenitor markers nestin, Sox2 and Pax6 transcription factors. When differentiated on fibronectin coated dishes in mitogen free culture conditions, the primary spheres from all three sources were able to generate neuron/glial ‐ like cells which expressed Nfl, Map2 and GFAP with varied efficiency. Self‐renewal potential of these progenitors was determined by secondary sphere formation. WJ‐ and BM‐derived neurospheres were able to self‐renew, while AD derived progenitors failed to do so. Comparison of the secretome profile suggested that WJ derived MSCs secrete more neurotrophic factors. The data suggest that human WJ derived MSCs can be induced to make neural progenitors with higher efficiency compared to BM and AD derived MSCs.

Administration of Adult Human Bone Marrow-Derived, Cultured, Pooled, Allogeneic Mesenchymal Stromal Cells in Critical Limb Ischemia Due to Buerger’s Disease: Phase II Study Report Suggests Clinical Efficacy

Critical limb ischemia (CLI) due to Buerger’s disease is a major unmet medical need with a high incidence of morbidity. This phase II, prospective, nonrandomized, open‐label, multicentric, dose‐ranging study was conducted to assess the efficacy and safety of i.m. injection of adult human bone marrow‐derived, cultured, pooled, allogeneic mesenchymal stromal cells (BMMSC) in CLI due to Buerger’s disease. Patients were allocated to three groups: 1 and 2 million cells/kg body weight (36 patients each) and standard of care (SOC) (18 patients). BMMSCs were administered as 40–60 injections in the calf muscle and locally, around the ulcer. Most patients were young (age range, 38–42 years) and ex‐smokers, and all patients had at least one ulcer. Both the primary endpoints—reduction in rest pain (0.3 units per month [SE, 0.13]) and healing of ulcers (11% decrease in size per month [SE, 0.05])—were significantly better in the group receiving 2 million cells/kg body weight than in the SOC arm. Improvement in secondary endpoints, such as ankle brachial pressure index (0.03 [SE, 0.01] unit increase per month) and total walking distance (1.03 [SE, 0.02] times higher per month), were also significant in the group receiving 2 million cells/kg as compared with the SOC arm. Adverse events reported were remotely related or unrelated to BMMSCs. In conclusion, i.m. administration of BMMSC at a dose of 2 million cells/kg showed clinical benefit and may be the best regimen in patients with CLI due to Buerger’s disease. However, further randomized controlled trials are required to confirm the most appropriate dose. Stem Cells Translational Medicine 2017;6:689–699

Preclinical safety & toxicity evaluation of pooled, allogeneic human bone marrow-derived mesenchymal stromal cells

Background & objectives: Administration of ex vivo-expanded human bone marrow-derived mesenchymal stromal cells (hBMMSC) obtained from single donors has shown therapeutic benefits in both preclinical and clinical studies. In this study, the safety, toxicity and biodistribution profiles of a pooled hBMMSC population, produced from three healthy donors were assessed in rodent and non-rodents. Methods: The pooled hBMMSC population was characterized by their expression of various cell surface markers, differentiation potential and immunomodulatory activity. To establish in vivo safety of the pooled cells, these were administered by various injection routes into rodents and non-rodents to determine overall toxicity, biodistribution and tumorigenic potential in a series of preclinical studies. Results: Single injections of hBMMSC at various doses through intravenous or intramuscular routes did not cause toxicity in rats and rabbits. In addition, repeat administration of hBMMSC was also well tolerated by rats, and no prenatal toxicity was observed by multiple administration in the same animal species. Ex vivo-expanded and cryopreserved hBMMSCs did not induce tumour formation in severe combined immunodeficient (SCID) mice. Interpretation & conclusions: Our results showed that the pooled hBMMSC population was non-toxic, non-teratogenic and non-tumorigenic in animals. Further studies need to be done to find out if it can be safely administered in human patients.

Mesenchymal Stem Cell Therapy for Peripheral Vascular Diseases

Adult multipotent mesenchymal stem or stromal cells (MSCs) have been at the forefront of basic and clinical research for years and have unique biological and immunomodulatory properties making them an attractive cell source for tissue regeneration and repair. MSCs have been reported to home to and accumulate around the damaged tissue, and the primary mode of action is believed to be mediated through paracrine activity. The secretome profile of MSCs include among others various anti-inflammatory and angiogenic growth factors, suggesting that these cells are potentially useful for treating peripheral arterial diseases (PAD) like critical limb ischemia (CLI). In addition, because of their non-immunogenic nature and potent immunosuppressive properties, MSCs have the ability to survive in an allogeneic environment. Recent clinical trial data using stem cells with angiogenic properties have shown some success in the treatment of PAD. Since bone marrow-derived MSCs (BMMSCs) have been the most well-characterized population of MSC with high angiogenic potential, we have developed an investigational medicinal product (IMP) using BMMSCs from normal adult healthy volunteers and have performed clinical trials with CLI patients. This review broadly describes the advancements made during the last several years with MSCs and other types of stem cells for the treatment of PAD, with special reference to CLI.